For the two-port network shown, the parameter Y₁₂ is equal to

Y (Admittance) Parameters:

They are also called the short circuit parameters, as they are calculated under short circuit conditions, i.e. at V1 = 0 and V2 = 0.

Expressed in Matrix Form as:

I1 = Y11V1 + Y12V2

I2 = Y21V1 + Y22V2

With the output short-circuited, i.e. V2 = 0, the two parameters obtained are:

With the input short-circuited, i.e. V1 = 0, the two parameters obtained are:

Analysis:

We can see that, 

Y₁₁ = YA + YC

Y₁₂ = Y₂₁ = -Y_C

Y₂₂ = Y_B + Y_C